This is the male. Although it has the “hook” at the end of the abdomen, it does not sting (thanks toEric Eaton). According to Bug Guide.net, “Larvae are parasitoids of white grubs (scarab larvae), especially May Beetles, Phyllophaga. Female lays one egg per grub in soil. Larvae hatches, penetrates host, first feeding on non-essential tissues, later feeding on essential organs and killing host. Pupae overwinter in soil and adults emerge in early summer, with one generation per year.” Typically found in fields, this one was floating in the water at Lock and Dam 14. Considering the parasitic nature of the larvae on Scarab beetles, maybe I should have brought this guy home to encourage some natural resistance to the Japanese beetle infestation I get every year (although I do not believe the Japanese beetles lay eggs / hatch larva in my area, they seem to just show up in droves as adults in July).

Photos taken with the Canon Digital Rebel XT / 350D and a Sigma 70-300mm Lens on July 25, 2009, on the Mississippi River near LeClaire, Iowa.